I was interested to read the report outlining the usefulness of thoracic ultrasound in the detection of a pneumothorax in a patient in cardiac arrest. I am unclear, however, on a couple of points raised by the authors when describing their case. Firstly, they describe difficulty in auscultating the patients chest due to widespread crepitus secondary to surgical emphysema. It is well known that the presence of surgical emphysema significantly limits the use of ultrasound because air (wherever it is) interferes with the transmission and interpretation of the generated ultrasound image. Secondly, the lung sliding sign, though useful, is relatively subtle and can be difficult to see even in optimal conditions and I would respectfully suggest that imaging during CPR is not optimal. Can the authors provide more information on how they overcame these particular practical issues as it would be useful in guiding relative novices such as myself who have only recently began to use ultrasound scanning on the ICU.

G. Price